Fix test workflow issues with WP_Mock, PHP 7.0 compatibility, and code style

includes/plugin.php

@@ -1 +1,54 @@
 <?php
+/**
+ * Main plugin class
+ *
+ * @package WPALLSTARS\PluginStarterTemplate
+ */
+
+namespace WPALLSTARS\PluginStarterTemplate;
+
+/**
+ * Plugin class
+ */
+class Plugin {
+
+	/**
+	 * Core instance
+	 *
+	 * @var Core
+	 */
+	private $core;
+
+	/**
+	 * Plugin file
+	 *
+	 * @var string
+	 */
+	private $plugin_file;
+
+	/**
+	 * Plugin version
+	 *
+	 * @var string
+	 */
+	private $version;
+
+	/**
+	 * Constructor
+	 *
+	 * @param string $plugin_file Main plugin file path.
+	 * @param string $version Plugin version.
+	 */
+	public function __construct($plugin_file, $version) {
+		$this->plugin_file = $plugin_file;
+		$this->version = $version;
+		$this->core = new Core();
+	}
+
+	/**
+	 * Initialize the plugin
+	 */
+	public function init() {
+		// Initialize plugin.
+	}
+}